(a) Field of the Invention
The present invention relates to a radio bearer deciding method of a mobile IPTV system.
(b) Description of the Related Art
In the Universal Mobile Telecommunications System (UMTS) Release 6, each cell allocates a constant amount of power allocated to the cell (e.g., 30% of a base station transmission power) to a forward access channel (FACH) and allocates remaining power to a dedicated channel (DCH) and a high speed downlink shard channel (HS-DSCH). The FACH is a multicast dedicated channel, and the HS-DSCH is a packet dedicated shared channel.
Also, the Release 6 introduces the multimedia broadcast and multicast service (MBMS). The MBMS shares a resource by simultaneously transmitting same data to a plurality of terminals through the FACH in the downlink.
The FACH that is a dedicated channel for providing the MBMS does not apply power control. That is, the FACH uses constant power irrespective of a number of service users requiring the MBMS.
However, if the MBMS is provided by using the FACH when there are a small number of service users requiring the MBMS, a large amount of power is wasted for them. Therefore, when the number of users to whom the multicast transmission method is provided is not big, the 3GPP UMTS has specified in the standard (TS 22.146) to selectively support the unicast transmission method. That is, in order to maximize the system capacity of each cell within the predefined total transmission power limit of a base station and efficiently use the radio resource, the 3GPP UMTS selects the unicast transmission method or multicast transmission method depending on the number of service users requiring the MBMS. Also, the 3GPP UMTS finds the number of service requesters corresponding to a per-channel threshold value through a simulation according to power allocated to the channel, and selects one transport channel of the DCH, HS-DSCH, and FACH as a channel for differently providing the MBMS. However, this radio bearer selecting method is based on the CDMA scheme.
Since recent mobile IPTV systems support the OFDM-based MBMS, a radio bearer deciding method for the OFDM scheme is required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.